1. Field of the Invention
The present invention relates to a compressor adapted to be disposed in a refrigeration cycle, such as a vehicle air conditioning apparatus, for use in compression of refrigerant gas.
2. Description of the Related Art
In general, a compressor has a crank chamber in which lubricating oil is normally stored for the purpose of supplying lubricating oil to various sliding component parts disposed in the crank chamber. However, as disclosed in Japanese Patent Provisional Publication No. 62-203980, since the compressor of this type has an gas extraction passage that communicates with the crank chamber and a suction chamber, an issue arises in that lubricating oil flows from the crank chamber to the suction chamber through the gas extraction passage.
If lubricating oil is carried from the crank chamber, the following two principal issues arise. First, if lubricating oil is carried from the crank chamber to result in shortage in oil to be supplied to the sliding component parts in the crank chamber, an adverse affect is caused in the sliding component parts. Second, if lubricating oil flows from the crank chamber into a heat exchanger (especially a condenser or an evaporator in the heat exchanger) in a refrigeration cycle through a path including the crank chamber→the suction chamber→the cylinder bore→the discharge chamber→the compressor exterior→the heat exchanger, lubricating oil adheres to capillary tubes of the heat exchanger, resulting in deterioration in a heat exchange efficiency.
In view of the above in mind, as disclosed in Japanese Patent Provisional Publication No. 58-158382, there is also a related art compressor with a structure wherein an outlet of an gas extraction passage is connected to a control valve that is expected to have the same function as an orifice. However, with the control valve of this related art technology, an opening and closing valve of the gas extraction passage is closed during an inoperative state of the compressor and, during operative state of the compressor, the opening and closing valve of the gas extraction passage is opened. As a result, even though oil is separated from gas, oil accompanied by gas flow is gradually flown out from a crank chamber too. Also, the presence of the control valve causes the gas extraction passage to be complicated in structure.